What is the recommended treatment for a patient with impetigo, considering severity, age, and potential allergies?

Treatment of Impetigo

For limited impetigo, start with topical mupirocin 2% ointment applied three times daily for 5 days; for extensive disease, treatment failure after 3-5 days, or systemic symptoms, switch to oral antibiotics such as dicloxacillin, cephalexin, or clindamycin (if MRSA suspected) for 5-10 days. 1, 2

Initial Treatment Selection Based on Disease Extent

Limited disease (few lesions, <100 cm² total area):

• Mupirocin 2% ointment applied three times daily is the most effective topical agent for impetigo caused by S. aureus and S. pyogenes 1
• Retapamulin 1% ointment applied twice daily for 5 days is an FDA-approved alternative for patients ≥9 months old with impetigo due to methicillin-susceptible S. aureus or S. pyogenes 3
• Bacitracin and neomycin are considerably less effective and should not be used 1
• The treated area may be covered with a sterile bandage or gauze dressing if desired 3

Extensive disease or specific indications for oral therapy:

• Switch to oral antibiotics if impetigo is extensive, not responding to topical therapy after 3-5 days, or associated with systemic symptoms 1
• Lesions on the face, eyelid, or mouth require oral antibiotics 1
• Oral therapy is preferred when there is a need to limit spread to others 1

Oral Antibiotic Selection Algorithm

For presumed methicillin-susceptible S. aureus (MSSA):

• Dicloxacillin 250 mg four times daily for adults; 12 mg/kg/day in 4 divided doses for children 1, 2
• Cephalexin 250-500 mg four times daily for adults; 25 mg/kg/day in 4 divided doses for children 1, 2
• Amoxicillin-clavulanate 875/125 mg twice daily for adults; 25 mg/kg/day of amoxicillin component in 2 divided doses for children 2
• Cefdinir can be considered as an alternative oral cephalosporin 2

For suspected or confirmed MRSA:

• Clindamycin 300-450 mg three times daily for adults; 10-20 mg/kg/day in 3 divided doses for children 1, 2
• Trimethoprim-sulfamethoxazole 1-2 double-strength tablets twice daily for adults; 8-12 mg/kg/day (based on trimethoprim component) in 2 divided doses for children 1, 2
• Doxycycline 100 mg twice daily for adults (not for children under 8 years) 2

Critical pitfall: Penicillin alone is not effective for impetigo as it lacks adequate coverage against S. aureus 1, 2

Duration of Therapy

• Topical treatment: 5-7 days 1
• Oral antibiotics: 5-10 days 1, 2

Special Population Considerations

Pediatric patients:

• Avoid tetracyclines (including doxycycline) in children under 8 years of age 1, 2
• For children with suspected MRSA, clindamycin 10-20 mg/kg/day in 3 divided doses is preferred 2
• Retapamulin is FDA-approved for patients ≥9 months old 3

Pregnant patients:

• Cephalexin is generally considered safe 1, 2
• Avoid tetracyclines 1

Penicillin-allergic patients:

• Clindamycin is the preferred alternative 1

Management of Treatment Failure

If no improvement after 3-5 days of topical mupirocin:

• Initiate oral antibiotics such as dicloxacillin, cephalexin, clindamycin, or amoxicillin-clavulanate 2
• Consider possible mupirocin resistance, especially in areas with high MRSA prevalence 2
• Obtain cultures from lesions to assess for MRSA or guide antibiotic selection 1, 2
• Re-evaluate if no improvement after 48-72 hours of oral therapy 2

For treatment failure with oral antibiotics:

• Consider hospitalization with IV antibiotics such as vancomycin for MRSA 2
• Linezolid is an option for children with MRSA resistant to clindamycin: 30 mg/kg/day in 3 doses for children under 12 years and 20 mg/kg/day in 2 doses for children 12 years and older 2

Infection Control Measures

• Keep lesions covered with clean, dry bandages 1
• Maintain good personal hygiene with regular handwashing 1
• Avoid sharing personal items that contact the skin 1

Important Caveats

Topical clindamycin cream should NOT be used for impetigo:

• Clindamycin cream lacks FDA indication for impetigo and is specifically approved only for acne vulgaris 1
• Topical clindamycin for acne has minimal systemic absorption (approximately 4% bioavailability), which is insufficient to treat bacterial skin infections 1
• Oral clindamycin is appropriate for impetigo, but topical clindamycin cream is not interchangeable 1

Disinfectants are inferior to antibiotics:

• Topical antibiotics are significantly better than disinfecting treatments 4
• Topical disinfectants should not be used for impetigo treatment 5, 6

Macrolide resistance:

• Macrolides (e.g., erythromycin) may have increasing resistance rates and should be used with caution 2, 5